Cooking units such as electric hobs, electric cookers, portable electric cookers or the like are usually provided with from two to four electric cooking plates each of which has an output of from 1000 to 2000 W so that food can be heated up relatively quickly on these cooking plates. A four-plate unit can therefore have a maximum output of 7 to 8 kW. This is often too much for a normal domestic mains supply, particularly if the mains voltage is only 120 volts. In addition, it is not possible to connect such a unit to a socket which is fused in the normal way. Cooking units have already been proposed which contain a power cooking plate with a high load and three cooking plates with a very low load which are intended for continued cooking. With this arrangement, the house-wife has to heat up each pan in succession on the one high power plate, e.g. bring the contents thereof to the boil, then transfer the pans to the three plates of lower power for continued cooking. This makes the cooking more difficult and demands particular attention.